1. Technical Field
The present invention relates to detecting circular objects in two-dimensional (2D) medical image data, and more particularly, to catheter electrode detection and tracking.
2. Discussion of the Related Art
Electrophysiology (EP) studies and ablation therapies are used to diagnose and treat heart arrhythmia, respectively. They involve the placement of a catheter through a patient's blood vessels to reach the heart. If treatment is necessary, electrodes on a catheter can be used to ablate specific positions. Ablation targets may be found based on electrical signals or based on anatomy. For example, paroxysmal atrial fibrillation is usually treated by pulmonary vein isolation. This involves placing isolation points around the pulmonary veins attached to the left atrium (LA). Bi-plane and mono-plane fluoroscopic X-ray images are used to guide the physician during the procedure. FIG. 1 shows one such image with an ablation catheter 110, a lasso catheter 120 and a coronary sinus catheter 130. In FIG. 1, the dark circular objects near the end of the catheters correspond to electrodes.
Bi-plane fluoroscopy allows for the acquisition of two fluoroscopic images taken at different viewpoints, thereby making it possible to triangulate three-dimensional (3D) points. Additionally, pre-operative 3D images can be used to augment fluoroscopy images and help the physician better locate the ablation region of interest. To further improve augmented fluoroscopy, catheter localization is helpful as it can facilitate motion correction of overlays and tagging of ablation points. Conventional tracking approaches typically require the physical modification of the catheter to include hardware to enable electromagnetic catheter tracking, for example. Although such devices do allow real-time tracking of catheters, they impose limitations on the catheters used and add cost to the procedure. Additionally, external hardware is usually required for tracking.
Computer vision approaches to catheter tracking may be able to offer many of the same benefits as electromagnetic tracking without the need for physical catheter modification at a much cheaper price point. However, such approaches require robust catheter detection in near real-time conditions.